Secondary barriers for aircraft are disclosed. An example secondary barrier includes a plurality of tracks to mount to a first monument in a cabin of an aircraft and a plurality of rods, where respective ones of the rods slidably engage respective ones of the tracks. The secondary barrier includes a panel coupled to respective ends of the rods. The rods to move relative to the tracks between a stowed position and a deployed position. The panel in the deployed position is to interface with a second monument in the cabin opposite the first monument. The rods are to extend between the first monument and the second monument when the secondary barrier is in the deployed position.